1. Field of the Invention
The present invention concerns the implementation of a network for conveying between network users material or immaterial entities referred to hereinafter as signals. These signals may be, for example, electromagnetic waves or electrical currents conveying data to be transmitted between the users or electrical power to be distributed or fluids such as a combustible gas, water or oil, etc.
A network of this kind comprises equipments adapted to perform various functions enabling these signals to be conveyed. These equipments may be, for example, microwave relay transmitter-receivers, telephone switching centers, electricity substations, pumping stations, etc. The distances between them depend on the distances between network users. They may be degraded in ways leading to partial or total failure of the network.
2. Description of the Prior Art
A known way of carrying out surveillance to enable effective network maintenance is to provide sensors adapted to produce data periodically or on demand. These sensors are referred to hereinafter as "surveillance sensors". This data may constitute a more or less direct representation of the functional capabilities of the equipments and other like data may represent characteristics of the signals conveyed.
The surveillance data must be acted on to establish a diagnostic. To be more precise, if an alarm indicates that the network is degraded, before undertaking any repair or exploratory work on any of the equipments in the network it is desirable to determine which equipment requires repair and, if this equipment is a composite unit, which of its capabilities is degraded, this determination constituting a diagnostic. It is already possible for a diagnostic to be established, at least in part, by a computer-based automatic diagnostic system. The use of a system of this kind has various advantages, especially from the points of view of network operating cost and security and speed of repair. A diagnostic system of this kind is described in the article "Expert Systems for AT&T Switched Network Maintenance" (Paul H. Callahan, AT&T Technical Journal, pp. 263-273, 1988). Also of relevance on this topic is a special issue of "British Telecom Technological Journal" (Vol 9, N.degree. 3, July 1991) on telecommunication network management.
The known diagnostic system receives surveillance data via a surveillance transmission system provided for this purpose. The diagnostic system systematically receives substantially all available surveillance data so that it can establish a diagnostic having the best possible attributes. The attributes of the diagnostic to be taken into consideration include its accuracy and the probability that it is correct.
In any network of this kind the cost of diagnosing faults can constitute a non-negligible part of total network operating costs. It includes the cost of installing, maintaining and operating the sensors, the surveillance transmission system and the diagnostic system.
Objects of the present invention are:
to reduce the average cost of the diagnostic, and/or PA1 to enhance the diagnostic by increasing the number of items of surveillance data available without increasing the capacity of the surveillance transmission system or the processing power of the diagnostic system.